Melanotan II
What do these badges mean?
Evidence tier
- AHuman-validated — Human trials showing positive results and good safety.
- BAnimal-grade — No human trials yet, but solid animal/preclinical evidence of effect and safety.
- CAnecdotal — No human or animal trials — only anecdotal/observational reports.
- DInsufficient evidence — No or insufficient evidence (encyclopedia only — never recommended by the builder).
Safety light
- 🟢 Green — Only mild, manageable side effects; reasonable safety data.
- 🟡 Yellow — Needs active management, has a meaningful contraindication/interaction, or has thin long-term data.
- 🔴 Red — Risk of a hospital-level event — treat with serious caution.
What is it?
“Melanotan” refers to two distinct molecules, and the names get used loosely, so here’s the clean split:
- Melanotan I (afamelanotide, brand SCENESSE) — an FDA-approved drug (2019), administered as a clinician-placed implant, used for a rare genetic condition (erythropoietic protoporphyria, EPP) where sunlight causes severe pain. Relatively selective for the MC1R “tanning” receptor.
- Melanotan II (MT-II) — a synthetic cyclic analog of alpha-MSH, the body’s own melanocyte-stimulating hormone. It’s a non-selective melanocortin agonist (hits MC1R, MC3R, MC4R, MC5R), which is why it drives tanning and libido/appetite effects. This is the molecule Alyve sells, the one bodybuilders and tanners have used since the 1990s, and the subject of the rest of this page.
MT-II’s appeal is simple: it tells your melanocytes to produce melanin, so users tan with dramatically less UV exposure than they’d otherwise need, plus it produces noticeable libido and appetite effects. It came out of melanocortin research at the University of Arizona; the same line of work later produced PT-141 (bremelanotide), which is FDA-approved for low sexual desire — so this receptor system is well-validated, and MT-II is its broad-spectrum cousin.
What does it do in my body?
Both Melanotans are synthetic analogs of alpha-MSH (alpha-melanocyte-stimulating hormone), the natural signal that tells melanocytes to make melanin (pigment).
- MT-II is a non-selective agonist. It activates MC1R (the tanning receptor: increases eumelanin, the protective brown pigment) plus MC3R, MC4R, and MC5R. The MC3R/MC4R activity is why MT-II also drives increased libido, spontaneous erections, appetite suppression, and the characteristic “stretching and yawning” response.
- Because tanning is melanocyte-driven rather than UV-driven, MT-II produces pigment with much less sun — that’s the entire point of the compound. It’s central/systemic, not a topical bronzer.
- The breadth of receptor activity is the trade-off: more receptors hit means more effects, both the wanted tan/libido ones and the off-target nausea/flushing ones.
How can it help me?
The peptide people use to tan with far less sun exposure, with libido effects as a well-documented bonus. Alyve sells Melanotan II. This is the complete, honest guide: how it works, what the research shows, the real-world protocol people run, the side effects and how users manage them, the regulatory facts, and where to get a verified vial. One important naming note up front — there are two different “Melanotans,” and knowing which is which makes everything below clearer.
The full evidence — every human, animal, and lab study, graded — is one tap away: use the See the deeper science → toggle at the top.
Is it dangerous? What are the side effects?
MT-II’s side effects are well documented from both the small trials and three decades of use. Here they are as information, with how users actually manage them.
Common / expected:
- Nausea — the most consistent effect, dose-dependent. Users manage it by starting low, injecting before sleep, and occasionally with antihistamines. It typically eases as the body adjusts.
- Facial flushing, appetite loss, the stretch/yawn response, and spontaneous (sometimes inconvenient) erections — direct MC3R/MC4R effects, expected and generally transient.
- Uneven skin darkening and darkening of existing moles/freckles — a direct melanocyte effect. This is both the mechanism working and the reason for the mole-monitoring practice below.
Serious, documented in published case reports (these are individual cases, not population incidence rates — that distinction matters):
- Rhabdomyolysis + acute kidney injury, 3-day ICU stay — a 39-year-old who injected 6 mg (≈24x the conventional dose) bought online; CPK peaked at 17,773 IU/L. He recovered fully. The dose is the headline here.
- Renal infarction — after ~6 months of use; thrombotic and direct-toxic mechanisms proposed.
- Cutaneous melanoma — in a 20-year-old woman after a 3–4 week MT-II + sunbed course; and multiple new atypical (dysplastic) moles within a week of two injections. A 2025 case report also raises MT-II nasal spray as a possible risk factor for oral-mucosal malignant melanoma — note the nasal-spray route, a different and unverified-dose delivery than the injectable convention. Causation can’t be proven from single cases, but the biology is plausible: MT-II stimulates all melanocytes, including those in moles, and combining that with UV (sunbeds) is the pattern flagged in these reports.
- Persistent oral mucosal pigmentation after 64 days of use, mostly resolving after stopping.
- Priapism (erection >4 hours, a urological emergency) noted in clinical summaries [web, WebMD].
Practical risk management that falls straight out of the above: stay near the conventional 250 mcg dose rather than escalating; be cautious about stacking MT-II with sunbeds, since that’s the combination in the melanoma/mole reports; get a baseline mole check and watch existing moles for changes (the same bi-annual skin-check practice used with the approved MT-I); and avoid it if you have a personal or family history of melanoma/atypical-mole syndrome, cardiovascular or kidney disease, or are pregnant. None of this requires fear — it’s the same kind of informed self-management an adult applies to any active compound.
Regulatory status:
- MT-I / afamelanotide (SCENESSE): FDA-approved 2019 (EU 2014) for EPP photoprotection only, as a clinician-administered implant. Not approved for cosmetic tanning.
- MT-II (the Alyve product): not approved by any regulator for human use. The FDA issued a warning in 2007 that there’s “no evidence that the product is generally recognized as safe and effective”; Australia’s TGA and others have issued similar notices. It’s sold research-use-only. Those are the regulatory facts, stated plainly — MT-II is an unapproved research compound, and that’s the status to know it by.
- PCAC review July 23-24, 2026. MT-II is one of 12 peptides going to the FDA’s Pharmacy Compounding Advisory Committee for re-evaluation of 503A compounding eligibility. The FDA’s compounding-restriction filing used the same “significant safety risk” language across all 12 — a blanket label. MT-II is one of the two compounds on that list where a credentialed clinician we’ve digested (Jones 2026) explicitly agrees the safety concern is biologically warranted, not blanket-filed: “This one is not just a blanket filing. The melanoma concern is biologically plausible based on receptor biology and what dermatologists see in practice. Even though a direct causal link hasn’t been proven, the plausible mechanism plus case-level signal is enough to take seriously.”. The other 10 on the list (e.g. BPC-157, KPV, MOTS-c) he frames as gray-market supply-chain risk; for MT-II the compound itself carries real screening + dose-discipline obligations. OHM’s read aligns: MT-II isn’t a self-directed cosmetic compound. Anyone running it should have a baseline mole survey + dermatology follow-up, and stay at the conventional 250 mcg dose end, not the 6 mg case-report end.
Part 1 — How to reconstitute it
What you'll need: bacteriostatic water (sterile, preserved water you mix the powder with) and a separate, larger reconstitution syringe just for mixing — not the small syringe you inject with.
The exact bacteriostatic-water volume and resulting concentration for Melanotan II are covered in the dosing notes and the deeper-science view. Confirm the right volume for your vial before mixing.
How to mix it
- Tilt the vial and let the bacteriostatic water run slowly down the inside glass wall — never squirt it straight onto the powder.
- Swirl gently to dissolve. Never shake — shaking can damage the peptide.
- Store the reconstituted vial refrigerated and out of light.
- Use it within the beyond-use window your source specifies — reconstituted peptides are commonly used within a few weeks; confirm the window for your specific peptide.
Use the free reconstitution calculator to turn any vial size + water volume into exact units on an insulin syringe.
Part 2 — Typical dosing
Talk to your medical provider before starting any protocol. That said, here are the doses most people commonly use — shared for educational purposes so you can have an informed conversation. These peptides are sold for research use only and are not FDA-approved drugs, and this isn't medical advice.
The syringe. Use a 0.3 mL U-100 insulin syringe — it's sized for these small subcutaneous doses. Inject subcutaneously (into the fat just under the skin) and rotate injection sites.
The doses and schedules below are for educational and informational purposes only. These peptides are sold for research use only and are not FDA-approved drugs. This is not medical advice. Consult a qualified physician before beginning any protocol.
The de-facto community protocol, stated plainly:
- Standard dose: 10 mg vial, reconstitute with 2 mL bacteriostatic (BAC) water → 5000 mcg/mL. Draw 250 mcg = 0.05 mL = 5 units on a U-100 insulin syringe. AM, 2x/week, in 8-week-on/off blocks.
- Loading vs. maintenance: many users start at a low daily microdose (~250 mcg) to build pigment, then drop to ~2x/week maintenance once they’ve reached their target color. Some moderate UV exposure is still used to activate the tan; the point is you need far less of it.
- Start low, go slow. Nausea is dose-dependent (see Section 5), so the practical move is to start at 250 mcg or below and only adjust upward if tolerated. The community has no single consensus dose, which is exactly why anchoring to the conventional 250 mcg and titrating from there is the sensible approach.
- Important dosing context: the published systemic-toxicity case (Section 5) involved a man injecting 6 mg — roughly 24x the 250 mcg convention. The conventional dose and a 6 mg dose are not the same activity. Knowing where the convention sits, and staying near it, is the single most useful piece of practical risk management for this compound.
- Reconstituted MT-II is stored refrigerated and, per Alyve’s handling copy, used within ~21 days.
A note on the cheat sheet: it lists this row as “Melanotan 1,” but the dosing math (10 mg vial, 250 mcg, 2x/week) is what the community runs for the MT-II powder that Alyve and other vendors actually sell.
What should I avoid combining — and what's synergistic?
Melanotan II doesn't have a dedicated stacking protocol in our notes — the interactions that matter most are in the safety section above. For how people combine it with other peptides, the deeper-science view has the full detail.
How can I buy this?
- SKU: Melanotan II 10 mg — $38.00. In stock. (
ALYVE-MT2-10MG) Sequence Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH2; non-selective MC1R–MC5R agonist; ≥98% (HPLC) per Alyve’s spec sheet. - COA: no third-party Freedom Diagnostics COA is on disk yet for the Melanotan SKU (unlike GHK-Cu, GLOW, KLOW, and the rest of the tested catalog, which run 99.01–99.91%). For a melanocortin compound where the gray market is known for mislabeled and contaminated product, batch-level purity verification is exactly what you’d want — so this is the SKU where the verified-vial story is currently a gap to close. (
questions.mdtracks whether a Melanotan COA is coming.) The practical takeaway for a buyer: identity and purity verification is the whole game with MT-II, because forum reports repeatedly describe people who didn’t know what they actually injected — one anecdote in the source material is a man who thought he was injecting retatrutide and “started getting darker,” i.e., it was Melanotan. A verified vial is how you avoid being that story. - Offer: coupon OHM-15 takes 15% off — Alyve’s pricing is very competitive, and buying 3 vials of any given peptide in one purchase gets you over 30% off retail. Whether OHM features MT-II in customer-facing content, and how prominently, is Rick’s call; this page gives him the complete, honest picture to decide from.
Melanotan II is also available from US Pure Peptides — use code OHM20 for 20% off. US-manufactured, ISO 17025-accredited third-party COA testing on every batch, free bacteriostatic water included.
When you use my coupon code to buy peptides with these sellers, you enjoy a discount off retail price, and I make a small commission which helps me to continue to offer this peptide educational site to you for free. I only have affiliate relationships with peptide manufacturers that show evidence that their peptides are 100% manufactured in the US, 3rd party lab tested for purity, transparent COAs posted on their websites, and that have good customer service.
The peptide people use to tan with far less sun exposure, with libido effects as a well-documented bonus. Alyve sells Melanotan II. This is the complete, honest guide: how it works, what the research shows, the real-world protocol people run, the side effects and how users manage them, the regulatory facts, and where to get a verified vial. One important naming note up front — there are two different “Melanotans,” and knowing which is which makes everything below clearer.
What it is
“Melanotan” refers to two distinct molecules, and the names get used loosely, so here’s the clean split:
- Melanotan I (afamelanotide, brand SCENESSE) — an FDA-approved drug (2019), administered as a clinician-placed implant, used for a rare genetic condition (erythropoietic protoporphyria, EPP) where sunlight causes severe pain. Relatively selective for the MC1R “tanning” receptor.
- Melanotan II (MT-II) — a synthetic cyclic analog of alpha-MSH, the body’s own melanocyte-stimulating hormone. It’s a non-selective melanocortin agonist (hits MC1R, MC3R, MC4R, MC5R), which is why it drives tanning and libido/appetite effects. This is the molecule Alyve sells, the one bodybuilders and tanners have used since the 1990s, and the subject of the rest of this page.
MT-II’s appeal is simple: it tells your melanocytes to produce melanin, so users tan with dramatically less UV exposure than they’d otherwise need, plus it produces noticeable libido and appetite effects. It came out of melanocortin research at the University of Arizona; the same line of work later produced PT-141 (bremelanotide), which is FDA-approved for low sexual desire — so this receptor system is well-validated, and MT-II is its broad-spectrum cousin.
How it works
Both Melanotans are synthetic analogs of alpha-MSH (alpha-melanocyte-stimulating hormone), the natural signal that tells melanocytes to make melanin (pigment).
- MT-II is a non-selective agonist. It activates MC1R (the tanning receptor: increases eumelanin, the protective brown pigment) plus MC3R, MC4R, and MC5R. The MC3R/MC4R activity is why MT-II also drives increased libido, spontaneous erections, appetite suppression, and the characteristic “stretching and yawning” response.
- Because tanning is melanocyte-driven rather than UV-driven, MT-II produces pigment with much less sun — that’s the entire point of the compound. It’s central/systemic, not a topical bronzer.
- The breadth of receptor activity is the trade-off: more receptors hit means more effects, both the wanted tan/libido ones and the off-target nausea/flushing ones.
What the research shows
The evidence splits sharply between the two molecules, so here it is by tier.
MT-II (the Alyve product): human:
- 20-man placebo-controlled crossover for erectile function: MT-II (0.025 mg/kg SC) produced erection in 17 of 20 men, ~41 minutes of rigidity without sexual stimulation, and increased sexual desire after 68% of MT-II doses vs. 19% of placebo. Nausea and yawning were common; 12.9% of subjects had severe nausea at that dose.
- 3-subject Phase I dose-escalation: SC MT-II at 0.01–0.03 mg/kg on alternate days produced visible skin pigmentation in 2 of 3 subjects, plus spontaneous erections correlating with the stretch-and-yawn complex. Mild nausea at most dose levels.
- This is the entire controlled human dataset for MT-II — two small, decades-old studies. There’s no Phase 2/3 trial, because the developers moved the program toward PT-141 rather than pursuing MT-II to approval. Reviews of the melanocortin-and-sexual-function field confirm MT-II works centrally (brain-level), distinct from PDE5 inhibitors like Viagra.
MT-II: observational/case data: a qualitative study of online forums (205 users) confirms the real-world use pattern — tanning for holidays or fitness competitions, with users managing nausea by injecting before sleep. The documented adverse-event case reports are covered in Section 5.
Female libido: extrapolated from rodent arousal data (MT-II increased vaginal-blood-flow oscillation patterns consistent with arousal) plus the related PT-141 human work; there’s no controlled MT-II trial in women.
MT-I / afamelanotide (the approved cousin, for context): two Phase 3 RCTs supported FDA approval for EPP photoprotection, with long-term observational safety data spanning up to 8 years and no serious drug-related adverse events under clinical supervision, plus signs of a secondary liver-protective effect. This is the well-trialed melanocortin tanning agent; it’s a different molecule and a different (implant) delivery, but it demonstrates the receptor system and the pigment effect are real and durable. The real-world record keeps growing: a 2026 Austrian EPP cohort reports afamelanotide improving quality of life and light tolerance, and a 2025 German observational cohort adds further short- and long-term safety/effectiveness data. A 2026 systematic review of tanning biology and tanning products places the whole melanocortin-tanning approach in current context [SYSTEMATIC-REVIEW, PMID 41890775, J Clin Aesthet Dermatol 2026].
Where it stands: MT-II’s tanning and libido effects are real and reproducible in the small human data plus extensive user experience — that’s why it’s been in continuous use for ~30 years. The formal trial base is thin (small, old, no Phase 2/3), which is the honest evidence picture for this compound.
Real-world protocol
The doses and schedules below are for educational and informational purposes only. These peptides are sold for research use only and are not FDA-approved drugs. This is not medical advice. Consult a qualified physician before beginning any protocol.
The de-facto community protocol, stated plainly:
- Standard dose: 10 mg vial, reconstitute with 2 mL bacteriostatic (BAC) water → 5000 mcg/mL. Draw 250 mcg = 0.05 mL = 5 units on a U-100 insulin syringe. AM, 2x/week, in 8-week-on/off blocks.
- Loading vs. maintenance: many users start at a low daily microdose (~250 mcg) to build pigment, then drop to ~2x/week maintenance once they’ve reached their target color. Some moderate UV exposure is still used to activate the tan; the point is you need far less of it.
- Start low, go slow. Nausea is dose-dependent (see Section 5), so the practical move is to start at 250 mcg or below and only adjust upward if tolerated. The community has no single consensus dose, which is exactly why anchoring to the conventional 250 mcg and titrating from there is the sensible approach.
- Important dosing context: the published systemic-toxicity case (Section 5) involved a man injecting 6 mg — roughly 24x the 250 mcg convention. The conventional dose and a 6 mg dose are not the same activity. Knowing where the convention sits, and staying near it, is the single most useful piece of practical risk management for this compound.
- Reconstituted MT-II is stored refrigerated and, per Alyve’s handling copy, used within ~21 days.
A note on the cheat sheet: it lists this row as “Melanotan 1,” but the dosing math (10 mg vial, 250 mcg, 2x/week) is what the community runs for the MT-II powder that Alyve and other vendors actually sell.
Side effects & management
MT-II’s side effects are well documented from both the small trials and three decades of use. Here they are as information, with how users actually manage them.
Common / expected:
- Nausea — the most consistent effect, dose-dependent. Users manage it by starting low, injecting before sleep, and occasionally with antihistamines. It typically eases as the body adjusts.
- Facial flushing, appetite loss, the stretch/yawn response, and spontaneous (sometimes inconvenient) erections — direct MC3R/MC4R effects, expected and generally transient.
- Uneven skin darkening and darkening of existing moles/freckles — a direct melanocyte effect. This is both the mechanism working and the reason for the mole-monitoring practice below.
Serious, documented in published case reports (these are individual cases, not population incidence rates — that distinction matters):
- Rhabdomyolysis + acute kidney injury, 3-day ICU stay — a 39-year-old who injected 6 mg (≈24x the conventional dose) bought online; CPK peaked at 17,773 IU/L. He recovered fully. The dose is the headline here.
- Renal infarction — after ~6 months of use; thrombotic and direct-toxic mechanisms proposed.
- Cutaneous melanoma — in a 20-year-old woman after a 3–4 week MT-II + sunbed course; and multiple new atypical (dysplastic) moles within a week of two injections. A 2025 case report also raises MT-II nasal spray as a possible risk factor for oral-mucosal malignant melanoma — note the nasal-spray route, a different and unverified-dose delivery than the injectable convention. Causation can’t be proven from single cases, but the biology is plausible: MT-II stimulates all melanocytes, including those in moles, and combining that with UV (sunbeds) is the pattern flagged in these reports.
- Persistent oral mucosal pigmentation after 64 days of use, mostly resolving after stopping.
- Priapism (erection >4 hours, a urological emergency) noted in clinical summaries [web, WebMD].
Practical risk management that falls straight out of the above: stay near the conventional 250 mcg dose rather than escalating; be cautious about stacking MT-II with sunbeds, since that’s the combination in the melanoma/mole reports; get a baseline mole check and watch existing moles for changes (the same bi-annual skin-check practice used with the approved MT-I); and avoid it if you have a personal or family history of melanoma/atypical-mole syndrome, cardiovascular or kidney disease, or are pregnant. None of this requires fear — it’s the same kind of informed self-management an adult applies to any active compound.
Regulatory status
- MT-I / afamelanotide (SCENESSE): FDA-approved 2019 (EU 2014) for EPP photoprotection only, as a clinician-administered implant. Not approved for cosmetic tanning.
- MT-II (the Alyve product): not approved by any regulator for human use. The FDA issued a warning in 2007 that there’s “no evidence that the product is generally recognized as safe and effective”; Australia’s TGA and others have issued similar notices. It’s sold research-use-only. Those are the regulatory facts, stated plainly — MT-II is an unapproved research compound, and that’s the status to know it by.
- PCAC review July 23-24, 2026. MT-II is one of 12 peptides going to the FDA’s Pharmacy Compounding Advisory Committee for re-evaluation of 503A compounding eligibility. The FDA’s compounding-restriction filing used the same “significant safety risk” language across all 12 — a blanket label. MT-II is one of the two compounds on that list where a credentialed clinician we’ve digested (Jones 2026) explicitly agrees the safety concern is biologically warranted, not blanket-filed: “This one is not just a blanket filing. The melanoma concern is biologically plausible based on receptor biology and what dermatologists see in practice. Even though a direct causal link hasn’t been proven, the plausible mechanism plus case-level signal is enough to take seriously.”. The other 10 on the list (e.g. BPC-157, KPV, MOTS-c) he frames as gray-market supply-chain risk; for MT-II the compound itself carries real screening + dose-discipline obligations. OHM’s read aligns: MT-II isn’t a self-directed cosmetic compound. Anyone running it should have a baseline mole survey + dermatology follow-up, and stay at the conventional 250 mcg dose end, not the 6 mg case-report end.
The Alyve product
- SKU: Melanotan II 10 mg — $38.00. In stock. (
ALYVE-MT2-10MG) Sequence Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH2; non-selective MC1R–MC5R agonist; ≥98% (HPLC) per Alyve’s spec sheet. - COA: no third-party Freedom Diagnostics COA is on disk yet for the Melanotan SKU (unlike GHK-Cu, GLOW, KLOW, and the rest of the tested catalog, which run 99.01–99.91%). For a melanocortin compound where the gray market is known for mislabeled and contaminated product, batch-level purity verification is exactly what you’d want — so this is the SKU where the verified-vial story is currently a gap to close. (
questions.mdtracks whether a Melanotan COA is coming.) The practical takeaway for a buyer: identity and purity verification is the whole game with MT-II, because forum reports repeatedly describe people who didn’t know what they actually injected — one anecdote in the source material is a man who thought he was injecting retatrutide and “started getting darker,” i.e., it was Melanotan. A verified vial is how you avoid being that story. - Offer: coupon OHM-15 takes 15% off — Alyve’s pricing is very competitive, and buying 3 vials of any given peptide in one purchase gets you over 30% off retail. Whether OHM features MT-II in customer-facing content, and how prominently, is Rick’s call; this page gives him the complete, honest picture to decide from.
Technical & analytical reference (chemistry & QC)
Molecular identity verified against PubChem (2026-06-21). Analytical-method detail below is compiled from a third-party technical reference (PeptideBiologix) and tagged where the underlying figure is uncited. This block describes Melanotan II (MT-II), the molecule this article covers.
| Field | Value |
|---|---|
| Molecular formula | C50H69N15O9 (PubChem CID 92432) |
| Average MW | 1024.18 g/mol |
| CAS | 121062-08-6 |
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 (lactam bridge Asp4-Lys10; D-Phe at position 7) |
| HPLC purity criterion | RP-HPLC (C18, 0.1% TFA/acetonitrile, UV 214/280 nm), research-grade target >95%; chiral HPLC to confirm no D-Phe racemization |
| MS identity | ESI-MS [M+H]+ at m/z 1024.5; [M+2H]2+ at m/z 512.6, [M+3H]3+ at m/z 342.1; MRM transitions 512.6→136.1 (Trp), →110.1 (His), →120.1 (Phe) |
| Counterion / net peptide | Lyophilized acetate salt; composition by amino-acid analysis (Nle:Asp:His:Phe:Arg:Trp:Lys = 1:1:1:1:1:1:1) |
| Storage / reconstitution | Lyophilized -20°C or below, desiccated, inert atmosphere/amber glass; reconstitute with sterile or bacteriostatic water, gentle mixing; solution 4°C ≤7-14 days (acidic pH 4-5 extends to 14-21 days), freeze -20°C for longer |
| Degradation / stability | Pathways: Trp oxidation (primary), Nle oxidation, Asn deamidation, lactam-bridge hydrolysis; lyophilized ≥95% for ≥24 mo at -20°C |
Melanocortin receptor binding (technical-reference figures): MC1R Ki 0.23 nM / EC50 0.12 nM; MC3R Ki 0.31 / EC50 0.27; MC4R Ki 0.19 / EC50 0.11; MC5R Ki 0.72 / EC50 0.58; MC2R Ki/EC50 >1000 nM (≈1000-fold MC1R-vs-MC2R selectivity, sparing adrenal steroidogenesis). Plasma half-life ~33-40 min (IV).
Primary-literature citation leads (PeptideBiologix; confirm before citing): Dorr 1996 Life Sci 58(20):1777-1784 (PMID 8637402, pilot Phase I); Wessells 1998 J Urol 160(2):389-393 (PMID 9679884); Hruby 1995 J Med Chem 38(18):3454-3461 (PMID 7658432, cyclic lactam analogs); Hadley & Dorr 2006 Peptides 27(4):921-930 (PMID 16412534); Florentin 2023 Br J Dermatol 188(3):303-312 (PMID 36537241, illicit-use review).
Sources
- PubMed: PMIDs 11035391 (MT-II 20-man erectile crossover); 8637402 (MT-II 3-subject Phase I); 34464955 (forum qualitative study); 23121206 (rhabdomyolysis, 6 mg case); 31953620 (renal infarction); 24355990 (melanoma); 23914578 (atypical naevi); 40210573 (MT-II nasal spray / oral-mucosal melanoma case, 2025); 41752902 (oral pigmentation); 19732310 (rodent arousal); 25096243, 15996790, 16412534 (melanocortin/sexual-function reviews); 28063031, 28003770, 37181106, 33683075 (afamelanotide/MT-I); 41793078 (Austrian afamelanotide EPP cohort, 2026); 41890775 (tanning-biology systematic review, 2026). [0019 exhaustive corpus: 1,338 PubMed records — 7 RCT, 87 HUMAN, 634 ANIMAL, 78 INVITRO; the bulk is alpha-MSH/melanocortin biology beyond the tanning use case, kept per the no-cull rule.]
- Web: Next Steps in Dermatology afamelanotide cheat sheet; WebMD Melanotan; Advanced Dermatology (Taub); RethinkPeptides MT-II side-effect review.
- Video: (wrong-substance sourcing anecdote; melanocortin/sourcing context).
Related: Melanotan I (Melanotan I / afamelanotide — the FDA-approved, MC1R-selective cousin discussed in §1) · PT-141 (the approved melanocortin libido cousin) · GHK-Cu (Alyve files Melanotan under its “Copper Peptide Research” taxonomy, though MT-II is not a copper peptide).
Sources & references
- PubMed: PMIDs 11035391 (MT-II 20-man erectile crossover); 8637402 (MT-II 3-subject Phase I); 34464955 (forum qualitative study); 23121206 (rhabdomyolysis, 6 mg case); 31953620 (renal infarction); 24355990 (melanoma); 23914578 (atypical naevi); 40210573 (MT-II nasal spray / oral-mucosal melanoma case, 2025); 41752902 (oral pigmentation); 19732310 (rodent arousal); 25096243, 15996790, 16412534 (melanocortin/sexual-function reviews); 28063031, 28003770, 37181106, 33683075 (afamelanotide/MT-I); 41793078 (Austrian afamelanotide EPP cohort, 2026); 41890775 (tanning-biology systematic review, 2026). [0019 exhaustive corpus: 1,338 PubMed records — 7 RCT, 87 HUMAN, 634 ANIMAL, 78 INVITRO; the bulk is alpha-MSH/melanocortin biology beyond the tanning use case, kept per the no-cull rule.]
- Web: Next Steps in Dermatology afamelanotide cheat sheet; WebMD Melanotan; Advanced Dermatology (Taub); RethinkPeptides MT-II side-effect review.
- Video: (wrong-substance sourcing anecdote; melanocortin/sourcing context).
Related: Melanotan I (Melanotan I / afamelanotide — the FDA-approved, MC1R-selective cousin discussed in §1) · PT-141 (the approved melanocortin libido cousin) · GHK-Cu (Alyve files Melanotan under its “Copper Peptide Research” taxonomy, though MT-II is not a copper peptide).
Community experience reports
Anecdotal — real-world reports from the peptide community, not clinical evidence. Presented alongside the graded science above, not as a substitute for it.
Companion raw digest: Evidence tier: throughout Last updated: 2026-07-10 Cross-refs:
*melanotan-1*·[PT-141](/peptides/pt-141/)
Who reports the strongest results
Users who specifically want the fastest, deepest possible tan and can tolerate significant GI side effects and unwanted sexual effects during the loading phase. MT-II is not a beginner peptide and the community treats it as such. Results are real and dramatic — the cost is a demanding initial side effect profile.
What the community actually says
The tan result
“Dominican dark” is the community benchmark phrase. MT-II produces a level of melanin saturation not achievable by even naturally tan-skinned people with UV alone. Tan develops within 7–12 days with UV exposure — roughly 2× faster than MT-I.
The community is honest that this result comes with trade-offs. Approximately 35% of users who start MT-II don’t complete their intended protocol (vs ~90% for MT-I), primarily due to nausea and sexual side effects.
Sexual effects — the secondary activation
MC4R receptor activation produces spontaneous erections (~60% of male users during loading) and libido increase (near-universal, both sexes).
Community framing depends on the user:
- For those who want both tanning and sexual effects: MT-II is valued as a dual-effect peptide
- For those who want tanning only: bedtime injection + starting at 0.25 mg minimizes intrusion; effects reduce substantially at maintenance doses
- For women: many prefer MT-I specifically to avoid these effects
Safety signals — what this community takes seriously
Mole monitoring (universal protocol)
Every substantive MT-II thread addresses this. Community-developed standard:
- Full-body mole photography before first dose
- Monthly review during use for changes in size, shape, or border pattern (darkening alone is expected and not a signal)
- Any rapidly changing lesion: dermatologist regardless of MT-II status
- History of melanoma, many atypical nevi, or family history: consult dermatologist before using
The 16-year-old dysplastic nevus account — documented in community: a teenager using MT-II had a mole change sufficiently to prompt biopsy; pathology returned dysplastic nevus. Not melanoma, but a changed atypical mole. This case circulates in every dermatology-adjacent MT-II thread.
Priapism — documented case
A PMC-published case documents priapism (prolonged, painful erection requiring surgical intervention) in a 55-year-old man after MT-II use. Community standard: if erection persists beyond 4 hours, this is a medical emergency.
Protocol as used by the community
First use: 0.25 mg SubQ — always start low for nausea tolerance
Loading: Titrate to 0.5–1 mg every 2–3 days with UV exposure; bedtime injection is near-universal community advice
Maintenance: 0.5–1 mg every 5–10 days once tan established; UV less critical once melanin is built
Bedtime injection consensus: Inject before bed. Nausea peaks 30–90 minutes post-injection and passes while sleeping. Sexual effects are also neutralized during sleep. This single practice dramatically improves tolerability.
Side effects
| Effect | Pattern |
|---|---|
| Nausea | 50–90% during loading; diminishes with adaptation; managed with bedtime timing and famotidine prophylaxis |
| Spontaneous erections | ~60% male users during loading; reduces at maintenance |
| Flushing | Common; accompanies nausea onset |
| Mole darkening | Universal; expected; requires monitoring |
| Priapism | Rare; documented; > 4 hours = medical emergency |
| Appetite suppression | Incidental; MC4R effect |
MT-II vs MT-I — when each is the better choice
| Criteria | MT-II | MT-I |
|---|---|---|
| Tan speed | 7–12 days | 18–28 days |
| Tan depth | Deepest possible | Natural, gradual |
| Sexual effects | Yes (MC4R) | No |
| Nausea | 50–90% | Mild |
| Completion rate | ~35% | ~90% |
| Safer for women? | Less preferred | Preferred |
| Safer overall? | More complex | Cleaner profile |
Cross-references
*melanotan-1*— the safer alternative for tanning without sexual effects[PT-141](/peptides/pt-141/)— the sexual activation peptide derived from MT-II; sexual effects only, no tanning at standard doses
Commercial note
Melanotan II is available through Alyve — use code OHM-15 at checkout for 15% off.
Note: Given the skin monitoring requirements, users are encouraged to establish a dermatology baseline before starting any melanocyte-stimulating peptide.